This invention provides novel antitumor demethylcantharidin platinum complexes. This invention also provides a composition comprising at least one of said demethylcantharidin platinum complexes and a suitable carrier. This invention provides a pharmaceutical composition comprising effective amount of at least one of the said demethylcantharidin platinum complexes and a pharmaceutically acceptable carrier. This invention provides a method of inhibiting the growth of tumorous cells comprising contacting the cells with an amount of said demethylcantharidin platinum complex effective to inhibit the growth of said tumorous cells. This invention provides a method of inhibiting the growth of tumorous cells in a subject comprising administering to the subject with an amount of the said demethylcantharidin platinum complexes effective to inhibit the growth of said tumorous cells in the subject. Finally, this invention provides methods for producing said demethylcantharidin platinum complexes.